The present invention relates to cellular telephone communication systems, and more particularly to a system and method that provides for dynamic switching between call handling options such as caller notification and forwarding.
A conventional cellular system consists of a Mobile Telephone Switching Office (MTSO) which is surrounded by a set of cell sites. A mobile subscriber establishes a radio frequency (RF) communications link with a cell site by initiating a call. Each of the cell sites is coupled to the MTSO. The MTSO is also coupled to the Public Switched Telephone Network (PSTN), by dedicated lines. The range of a particular cellular service is determined by the geographic location of cell sites. When a subscriber to a cellular mobile telephone service leaves the range that is covered by his home service area and enters a foreign service area, calls that are received need to be handled in an appropriate manner. For example, the caller could be informed of the location of the subscriber; the calls could be forwarded directly to the subscriber; or the calls could be routed through the subscriber's voice mail service.
The forwarding of calls directly to the subscriber is not always appropriate, because in the present cellular telephone environment, the subscriber pays for the cost of the call. This means that a subscriber may be receiving calls that he does not want to receive and that he has to pay for. For this reason, subscribers frequently have calls sent to a voice mailbox or have the caller place the call directly to a foreign service area, in which case the caller would pay the long distance telephone charges. A subscriber using a cellular telephone in a foreign service area is generally referred to as a "roamer".
In order for a subscriber to instruct a caller to call a roaming subscriber, the subscriber would have to manually inform each potential caller of the roamer access number of the cellular telephone system that the roamer is using. Since the roamer could be moving from one roamer site to another, this is not always practical. Call delivery systems provided by some switch manufacturers (such as Motorola, AT&T and Ericsson) as well as the Follow Me Roaming product offered by GTE reduce this inconvenience to some extent but do not provide options of the present invention.
It is therefore a principal object of the present invention to provide a cellular telephone system and method that dynamically switches between call handling options.
Another object of the present invention is to provide a cellular telephone system and method that automatically initiates call forwarding to a foreign service area after a subscriber places a first call in the foreign service area or enters a foreign service area with the cellular phone switched on.